Testing equipment may be used to accurately generate and measure the noise parameters of a device under test (DUT). The noise parameters of a component are usually specified in terms of a noise factor F. The noise factor of a device is defined as the ratio of the signal-to-noise ratio available from the DUT output to the signal-to-noise ratio of the DUT input, at a standard reference temperature of 290 degrees Kelvin. Noise factor is often expressed in dB, which is sometimes referred to as a noise figure. Noise figure testing equipment typically includes a noise source that is cycled on and off to provide two power levels. The noise source results in a noise signal that must be matched to the DUT as closely as possible. Typical noise sources, however, have high voltage standing wave ratios, which lead to inaccuracy in the resulting noise figures. Additionally, different excess noise ratios may be required for the testing of different devices. Accordingly, many different noise sources may be required to test different devices.